In a gas bag which is known from GB-A-2 243 119 two limiting straps are provided which are connected with the wall of the bag by each of two ends of each strap in the region of the rim. The rim itself is additionally surrounded by a reinforcement layer which reduces the mechanical and also the thermal stress of the wall and of the limiting strap in the region around the inflation opening. With the inflation of hot gas, the rim is subjected to high thermal stresses, for which reason such reinforcement layers are usual.